A crepuscular bird, the nightjar (Caprimulgus europaeus) has finely patterned tree-bark like cryptic plumage that provides excellent camouflage in the daytime when it is inactive. Adults have a flat, wide head, small bill and large eyes that enable them to see in low light levels. Males can be distinguished from females by their white wing patches. Due to their long wings and tail, nightjars are very agile fliers (2). The scientific name Caprimulgus means 'goat sucker'; the species was fabled to milk goats due to their wide, soft mouths and habit of feeding near grazing animals. This superstition is ancient, dating back to Aristotle. The common name 'nightjar' refers to the loud jarring or 'churring' call of the male, which can contain 1900 notes per minute. A 'coo-ik' call is also given in flight (4).
Nightjars return from Africa in late April and May. Upon return, males attract a mate and establish a territory by calling. During courtship males fly around a female, often wing clapping or gliding with the tail spread out and wings held up. Nests are selected by males and are usually a shallow scrape on bare ground amongst heather or bracken. Eggs are laid between mid-May and mid- July. A typical clutch consists of one to three eggs, and if the first brood is produced early in the season, a second brood may be possible. The migration to Africa starts in August and September (2).
Nightjars hunt for insects on the wing at dusk and dawn, their agility allows them to perform rapid twists and turns in pursuit of their prey. Most of the diet consists of moths, flies, craneflies, beetles, and ants. Nightjars have an unusual serrated middle claw which they use to preen their feathers (2).
In the UK the nightjar is at the western extreme of its breeding range, which extends to China and Mongolia in the east, southern Scandinavia in the north and south to North Africa. It is a summer visitor to the UK, and winters in Africa. The breeding range in the UK has contracted from the north and west, but strongholds remain in southern England and East Anglia, there are also scattered populations as far north as Scotland (3).
Nightjars feed over a range of habitats such as freshwater wetlands, orchards and even gardens. However the most important habitats for the species are lowland heathland and young forestry plantations. Acidic heathland on gravely or sandy soils support strong nightjar populations in the south of Britain (3).
The nightjar is classified as Least Concern (LC) on the IUCN Red List (1). Listed under the Birds of Conservation Concern Red List, Annex 1 of the EC Birds Directive, Appendix II of the Bern Convention and protected in the UK under the Wildlife and Countryside Act 1981 (3).
The nightjar has been declining in both numbers and range in the UK since the beginning of the 20th century, and in 1981 the population reached its lowest level, with just 2,100 males recorded. Between 1968 to 1972 and 1992 the range decreased by 52 percent. Despite a partial recovery (numbers were up to 3,400 males in 1992), this species is still threatened. A loss of suitable breeding and foraging habitat is thought to have been a major cause of the decline; 40 percent of England's lowland heathland has been lost since the 1950s, and existing habitat still faces pressures from housing and road developments. It is also thought that a reduction in insect prey availability caused by climatic factors and pesticide use has played a role in the decline of the nightjar (3). Other contributory factors may be predation by adders (Vipera berus), lack of appropriate management on existing heathland sites leading to scrub invasion, and poor winter survival in the nightjar's African wintering grounds (2).
Nightjars breed on a number of RSPB nature reserves where management techniques are used to benefit the species. These techniques include the thinning of encroaching scrub, leaving patches that can be used as nesting sites and increasing the area of short heather available for nesting. The nightjar is a UK Biodiversity Action Plan species, this plan aims to halt the decline, and increase the numbers to 4,000 churring males by 2003 (5). Main areas of work have included the protection of existing lowland heathland and foraging habitats, creation of new habitats, and the promotion of sympathetic forestry management practices and agricultural systems in the wider countryside (2). Conservation action targeted at the nightjar will be likely to help the woodlark (Lullula arborea) (5).
Colouration that makes animals difficult to detect against their background. The colouration may provide camouflage against a background or break up the outline of the body. Both can occur in a single animal, and tend to reduce predation.
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